AP: Mexican drug cartels infiltrating the United States

Mexican drug cartels are dispatching some of their trusted agents to live and work deep inside the United States.

The ruthless syndicates have long been the nation's No. 1 supplier of illegal drugs.

But in the past, their operatives rarely ventured beyond the border, preferring to use unaffiliated middlemen to smuggle cocaine, marijuana and heroin.

But a wide-ranging Associated Press review of federal court cases and government drug-enforcement data, plus interviews with top law enforcement officials, indicate the groups have begun deploying agents from their inner circles to the U.S. Cartel operatives are suspected of running drug-distribution networks in at least nine non-border states, often in middle-class suburbs in the Midwest, South and Northeast.

If left unchecked, authorities say, the move could make the syndicates harder than ever to dislodge.